Ed's experience mirrors my own: vehicle batteries charge directly and discharge directly into the 28 Vdc bus and the only interposed electronics is protection circuitry built into the battery enclosure, while man-pack batteries charge from an external charger that converts its input potential into that required by the battery. However, even for these man-pack batteries, the protection circuit is necessarily built into the battery enclosure itself.
The above is fact, what follows is my opinion. The complex microprocessor-based circuitry that monitors the charge/discharge process and is the "victim" in terms of rf susceptibility and the "culprit" in terms of rf emissions is unnecessarily complex and a result of engineering education stressing digital designs over analog. If there was ever a classic analog design (including some simple TTL circuits but not a clocked system) it would be monitoring the input voltage and current and output current and using a simple comparator to decide when an input or output was beyond a threshold and to open or close a switch. Such an approach would not eliminate susceptibility of course, but it would eliminate all the steady-state emissions. Ken Javor Phone: (256) 650-5261 > From: Ed Price <[email protected]> > Date: Sun, 10 Mar 2013 03:40:06 -0700 > To: <[email protected]> > Subject: RE: [PSES] Immunity and emissions below 150 kHz and lithium batteries > > The cells that I have worked with have had a certain amount of internal > "intelligence" (a microprocessor with cell monitors and often, status > indicators, self-test controls and a communications interface, possibly even > internal fusing), but the charger was not part of the cell package. For our > man-pack devices, there was a desk-top charging station. For our vehicle > devices (including aircraft), the battery, switching power supply (which was > the source of battery charging when vehicle power was available) and other > functional devices were all mounted into a single sturdy box. In the vehicle > configuration, nothing ever could get intimately close to any of the active > boxes, and the external case allowed for a layer of shielding and filtering. > We also used shielding in the man-packs, but maybe we were just lucky to > never have a battery "run-away" failure. We did have man-pack battery > failures, but they were all of the "dead battery" kind. (The battery > controllers themselves sometimes proved very vulnerable, lacking radiated > immunity, but they always failed by disabling the battery; no dying > controller ever forced the cells into a conflagration.) > > Ed Price > WB6WSN > Chula Vista, CA USA > > -----Original Message----- > From: John Woodgate [mailto:[email protected]] > Sent: Saturday, March 09, 2013 3:14 PM > To: [email protected] > Subject: Re: [PSES] Immunity and emissions below 150 kHz and lithium > batteries > > In message <cd60f96a.3e1a4%[email protected]>, dated Sat, 9 Mar > 2013, Ken Javor <[email protected]> writes: > >> In my experience the charger is built into the battery as a stand-alone >> unit. > > Perhaps that isn't the wisest arrangement. Didn't someone post that the > battery and charger are made by different people? > -- > OOO - Own Opinions Only. See www.jmwa.demon.co.uk SHOCK HORROR! > Dinosaur-like DNA found in chicken and turkey meals John Woodgate, J M > Woodgate and Associates, Rayleigh, Essex UK > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://listserv.ieee.org/request/user-guide.html > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://listserv.ieee.org/request/user-guide.html > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
